A radial piston pump for high-pressure fuel delivery in fuel injection systems of internal combustion engines, in particular for a common rail injection system, is already known from DE 198 48 035 A1. The radial piston pump has a housing in which a drive shaft is mounted. The drive shaft has an eccentric section on which a reciprocating ring is mounted. Supported on the reciprocating ring there are preferably mounted a plurality of pump pistons which can be displaced radially with respect to the drive shaft longitudinally in the pump housing. Each pump piston is assigned a suction valve and a delivery valve. Fuel from the low-pressure area is supplied to the pump piston via the suction valve. After the pressure has built up, the compressed fuel is diverted via the delivery valve.
A radial piston pump of this kind typically has connected ahead of it a fuel pre-feeder pump which supplies the fuel from the fuel tank to the high-pressure pump. The fuel pre feeder pump is usually driven by an electric motor or via the camshaft. In the case of the camshaft drive, the pre-feeder pump can be mounted directly on the camshaft or be driven via a belt. Because of the limited space conditions in the engine compartment it is necessary for the high-pressure fuel pump and the pre-feeder pump to be of as compact a design as possible.
DE 197 36 160 A1 therefore proposes disposing the fuel pre-feeder pump on or in the pump housing of the radial piston pump and driving same via the drive shaft of the radial piston pump. Toward that end, a clutch is inserted between the drive shaft of the radial piston pump and the shaft of the pre-feeder pump.